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51.
Sun W Li S Mao J Guo Z Liu H Dou S Yu X 《Dalton transactions (Cambridge, England : 2003)》2011,40(21):5673-5676
Successful synthesis and investigation of a new material that uses copper-metal-organic frameworks (Cu-MOFs) as the template for loading LiBH(4) are reported. The nanoconfinement of LiBH(4) in the pores of Cu-MOFs results in an interaction between LiBH(4) and Cu(2+) ions, enabling the LiBH(4)@Cu-MOFs system to achieve a much lower dehydrogenation temperature than pristine LiBH(4). 相似文献
52.
Tao Li Yunyou Zhou Junyong Sun Dongbao Tang Shixue Guo Xueping Ding 《Mikrochimica acta》2011,175(1-2):113-119
We have developed a simple method for the preparation of highly fluorescent and stable, water-soluble CdTe quantum dots in sol-gel-derived composite silica spheres that were coated with calix[6]arene. The resulting nanoparticles (NP) were characterized in terms of UV, fluorescence and FT-IR spectroscopy and by TEM. The results show that the new NPs display more intense fluorescence intensity and are more stable than its precursors of the type SiO2/CdTe. In addition, the new NPs exhibit a higher selectivity for the determination of Hg2+ than for other metal ions. Under the optimum conditions, the relative fluorescence intensity decreases with the concentration of Hg2+ in the range from 2.0 to 14.0?nmol?L?1 and the detection limit is 1.55?nmol?L?1. The method is based on the quenching of fluorescence by Hg2+ and expected to serve as a practical fluorescence test for rapid detection of Hg2+. A mechanism is suggested to explain the inclusion process by a Langmuir binding isotherm, and fluorescence quenching is best described by the Stern-Volmer equation. Figure
The Scheme suggests that we synthesis of CdTe nanocystals in sol-gel-derived composite silica spheres coated with Calix[6]arene (C[6]/SiO2/CdTe NPs). The new C[6]/SiO2/CdTe NPs display more intense fluorescence intensity and are more stable than its precursors of the type SiO2/CdTe NPs. Under the optimum conditions, the relative fluorescence intensity decreases with the concentration of Hg2+. The C[6]/SiO2/CdTe NPs as fluorescent probes can be used for ultrasensitive, highly selective, simple, convenient and rapidly efficient detection of extremely trace amount of heavy metal ion Hg2+. 相似文献
53.
LaFeO3修饰和O3处理对Au/Al2O3催化剂在CO氧化反应中热稳定性的影响 总被引:2,自引:0,他引:2
通过等体积浸渍法并分别经过H2和O3活化制备了系列1·1%Au/LaFeOx/Al2O3催化剂,考察了其在550℃经1·0%CO原料气处理后的CO氧化活性.Fe和La的引入虽然使1·1%Au/Al2O3的初始活性降低,但提高了其高温稳定性.在550℃经1·0%CO原料气预处理2h后,H2活化的1·1%Au/Al2O3在室温完全失活,而同样条件处理的1·1%Au/2%LaFeO3/Al2O3仍能将65%CO转化;这可能是由于LaFeO3以钙钛矿形式单层分散在Al2O3表面而导致的.O3活化能进一步提高催化剂的稳定性,在550℃经原料气预处理后,O3活化的1·1%Au/2%LaFeO3/Al2O3的活性高于1·1%Au/Al2O3和H2活化的1·1%Au/2%LaFeO3/Al2O3.1·0%CO原料气预处理10h后,H2活化的1·1%Au/2%LaFeO3/Al2O3完全失活,而O3活化的催化剂仍具有40%的转化率,这可能是由于O活化使得催化剂中存在部分氧化的金,增强了金属与载体间的相互作用. 相似文献
54.
The palladium-catalyzed tandem arylation of O-homoallylhydroxylamines with 2 equiv of aryl bromides was examined. With Pd2(dba)3 (1 mol %) as the catalyst, Xantphos (2 mol %) as the ligand, and NaOt-Bu as the base, the reactions of O-homoallylhydroxylamines with aryl bromides via sequential N-arylation/cyclization/C-arylation in toluene afforded the corresponding N-aryl-3-arylmethylisoxazolidines in good yields with excellent diastereoselectivity. 相似文献
55.
SnS2 Nanoplatelet@Graphene Nanocomposites as High‐Capacity Anode Materials for Sodium‐Ion Batteries 下载免费PDF全文
Xiuqiang Xie Dr. Dawei Su Shuangqiang Chen Jinqiang Zhang Dr. Shixue Dou Prof. Dr. Guoxiu Wang 《化学:亚洲杂志》2014,9(6):1611-1617
Na‐ion batteries have been attracting intensive investigations as a possible alternative to Li‐ion batteries. Herein, we report the synthesis of SnS2 nanoplatelet@graphene nanocomposites by using a morphology‐controlled hydrothermal method. The as‐prepared SnS2/graphene nanocomposites present a unique two‐dimensional platelet‐on‐sheet nanoarchitecture, which has been identified by scanning and transmission electron microscopy. When applied as the anode material for Na‐ion batteries, the SnS2/graphene nanosheets achieved a high reversible specific sodium‐ion storage capacity of 725 mA h g?1, stable cyclability, and an enhanced high‐rate capability. The improved electrochemical performance for reversible sodium‐ion storage could be ascribed to the synergistic effects of the SnS2 nanoplatelet/graphene nanosheets as an integrated hybrid nanoarchitecture, in which the graphene nanosheets provide electronic conductivity and cushion for the active SnS2 nanoplatelets during Na‐ion insertion and extraction processes. 相似文献
56.
CHENG SHIXUE 《高校应用数学学报(英文版)》1994,9(2):121-126
ANEWCHARACTERIZATIONOFTHEBINOMIALSEQUENCE¥CHENGSHIXUEAbstract:Inthispaper,anewcharacterizationofthebinomialsequenceanditsequi... 相似文献
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本文对滑动轴承挤压油膜阻尼器的关键技术问题进行了大量的试验研究,结合理论分析,设计出结构简单合理、性能可靠的阻尼器。并提出了适合于工程设计的结构参数。 相似文献
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60.
迄今为止,氦气几乎是气相色谱-质谱联用仪运行中唯一可选的载气.本文使用气相色谱-质谱联用仪考察了氢气和氦气分别作为载气时,对5种有机磷农药混合标准溶液的检测,以确定氢气代替氦气作为气相色谱-质谱联用仪载气用于有机磷农药分析的可行性.用工作站自带解卷积软件(自动质谱解卷积鉴定系统,AMDIS32),结合自建"有机农药质谱库"对结果进行了解析,而后用SPSS统计软件对数据进行了聚类分析.结果发现,以氢气为载气时虽然出峰稍快,但色谱峰分离度较低,解良度较低,且待测物信号不稳定,测定准确度较低,有些化合物甚至检测不到.因此以氢气为载气分析有机磷农药时应对测定准确度、信号稳定性、安全性等诸多因素进行慎重考虑. 相似文献